In accordance with a rapid spread of information relevant apparatuses and communication apparatuses such as a personal computer, a video camera and a portable telephone in recent years, the development of a battery to be utilized as a power source thereof has been emphasized. The development of a high-output and high-capacity battery for an electric automobile or a hybrid automobile has been advanced also in the automobile industry. A lithium battery has been presently noticed from the viewpoint of a high energy density among various kinds of batteries.
A liquid electrolyte including a flammable organic solvent is used for a conventionally commercialized lithium battery, so that the installation of a safety device for restraining temperature rise during a short circuit and the structure for preventing the short circuit are necessary therefor. In contrast, the flammable organic solvent is not used in a lithium battery such that the liquid electrolyte is replaced with a solid electrolyte layer to all solidify the battery, so that the simplification of the safety device can be intended.
Patent Literature 1 discloses a method for producing a sulfide solid electrolyte material comprising steps of: an amorphizing step of obtaining a sulfide glass by amorphization of a raw material composition that contains at least Li2S, P2S5, and LiI, so as to obtain a sulfide glass, and a heat treatment step of heating the sulfide glass. The object of this technique is to provide a sulfide solid electrolyte material having high Li ion conductivity.